1. Field of the Invention
The present invention relates to an image comparing apparatus and a method therefor, an image retrieving apparatus, as well as a program and a recording medium. More specifically, the present invention relates to an image comparing apparatus and method for comparing an image compressed and coded according to JPEG (Joint Photographic Experts Group) 2000 system or the like with a specific image to make a matching decision or similarity decision. Further, the present invention relates to an image retrieving apparatus and method, program and recording medium for retrieving an image substantially matching with a specific image from among video contents compressed and coded according to JPEG 2000 system or the like.
2. Description of the Related Art
In related art, there has been required a technique for retrieving an image substantially matching with a specific image from among unknown video contents with the specific image as search query in order to retrieve video contents, for example. In Japanese Patent Application Laid-Open No. 2004-45565 described below, there is proposed a technique for extracting the characteristic amount for each short time frame from video contents to configure a characteristic vector, and comparing the characteristic vector with a characteristic vector of a specific image, thereby retrieving an image substantially matching with the specific image from the video contents.
In recent years, in many cases, an image has been directly photographed in digital to be subjected to image compression for recording along with widely use of products such as digital cameras or digital camcorders. Further, a television program is digitalized to be subjected to image compression, and is saved as archives. It was decided in 2004 that JPEG 2000 system is adopted as image compression method in standardizing digital cinemas, so that many movie films have been digitalized and been compressed and coded according to JPEG 2000 system for use.
There would be an increasing need to retrieve an image substantially matching with a specific image from among many images compressed and coded according to JEPG 2000 system. There is assumed an increasing need to retrieve an image substantially matching with a specific image from among video contents compressed and coded according to JPEG 2000 system. However, in the related art as in Japanese Patent Application Laid-Open No. 2004-45565, there was an issue that since the images or video contents need to be completely decoded prior to retrieval, the amount of calculation increases for the entire processing.
Thus, in Japanese Patent Application Laid-Open No. 2006-285615 described later, there is disclosed an image comparing apparatus and method for making a matching decision or similarity decision with a specific image without completely decoding an image compressed and coded according to JEPG 2000 system or the like. Further, there are disclosed an image retrieving apparatus and method, as well as program and recording medium for retrieving an image substantially matching with a specific image without completely decoding video contents compressed and coded according to JPEG 2000 system or the like.
The technique described in Japanese Patent Application Laid-Open No. 2006-285615 includes a first characteristic amount extracting means for extracting the number of zero bit planes for each code block from a JPEG 2000 code stream, a coding parameter extracting means for extracting coding parameters from the code stream, a second characteristic amount extracting means for performing wavelet conversion and quantization on a specific image based on the coding parameters, and then dividing a quantization coefficient into code blocks to extract the number of zero bit planes for each code block, and a comparing means for comparing the number of zero bit planes for each code block of the code stream with the number of zero bit planes for each code block of the specific image between the code blocks at the same position to decide whether the code stream substantially matches with the specific image depending on a comparison result.